Decimal Mint marks are easy
‘C’ mint mark (identified as minted in Canberra)
‘S’ (Sydney), ‘B’ (Brisbane), ‘A’ (Adelaide), and ‘M’ (Melbourne)
Australian pre decimal coins have been struck at a number of mints both in Australia and abroad.
To help identify from which mint a coin originates each mint adds a mark to the coin different from other mints. The mint mark is usually located near the date on the coin. There are some exceptions to this which are noted as they arise.
Mint marks on gold sovereigns:
M - Melbourne Victoria
S - Sydney New South Wales
P - Perth Western Australia
On both 1/2 sovereigns and full sovereigns with the St. George reverse the mint mark appears on the lower side of the ground above the centre of the date.
Sydney mint 1/2 sovereign and sovereigns do not have a mint mark.
1/2 sovereigns minted between 1871 and 1887 with the shield reverse have the date on the obverse and the mint mark on the reverse under the shield
Full sovereigns minted between 1871 and 1887 with the shield reverse have the date on the obverse and the mint mark on the reverse under the shield
Mint marks on pre decimal copper coins:
H - Heaton Mint in London, England used on 1/2 pennies 1912, 1914 and 1915 and pennies in 1912 and 1915 only.
I - On the reverse just above the date indicates Calcutta, India. This was used for 1/2 pennies in 1916, 1917 and 1918 and for pennies in 1917 and 1918.
I - On the obverse just below the Kings effigy indicates Bombay, India and was used for both 1/2 pennies and pennies for the years 1942 and 1943. These coins also have a dot before and a dot after the wording Half Penny and Penny respectively.
Dots - One penny 1919 with a dot below the bottom scroll indicates Melbourne mint.
One Penny 1919 with dot over the top scroll and dot below the bottom scroll indicates Melbourne mint.
One Penny 1920 dot over the bottom scroll indicates Sydney mint
One Penny 1920 dot below the bottom scroll indicates Melbourne mint
One Penny 1920 dot over the top scroll indicates Melbourne mint
One Penny 1920 dot over the top scroll and below the bottom scroll indicates Melbourne mint.
For 1/2 pennies A dot after the A of Australia indicates Perth mint and was used in 1952 only.
A dot after the Y of Half Penny indicates Perth mint and was used in 1942, 1945, 1946, 1947, 1948, 1949, 1950 and 1951.
For pennies a dot after the A of Australia indicates Perth mint and was used in 1952 and 1953.
A dot after the Y of Penny indicates Perth mint and was used from 1941 to 1945, 1947, 1948, 1950, 1951 and 1955 to 1964 inclusive.
PL - In 1951 some of our 1/2 pennies and some of our pennies were minted at the London mint and this is indicated by a PL which appears just after the Y of Half Penny and Penny respectively.
K.G - All pennies with a Kangaroo reverse, include as part of their design the letters KG which appear in the field just above the Kangaroos tail. Coins minted at the Perth mint during 1940 and 1941 have a dot between the K and the G distinguishing them as coins struck in Perth. This dot is not always clearly defined and can appear as anything from a clear dot to a low barely distinguishable lump.
Mint marks on pre decimal silver coins:
H - Heaton Mint in London, England used on one shilling in 1915 and florin in 1914 and 1915.
M - Melbourne mint used on the Threepence 1916 to 1921 inclusive, Sixpence 1916 to 1920 inclusive, Shilling 1916, 1917, 1918 and 1920, Florin 1916 to 1919 inclusive.
S - San Francisco Threepence 1942 to 1944 inclusive, Sixpence 1942 to 1944 inclusive, Shilling 1942 to 1944 inclusive, Florin 1942 to 1944 inclusive.
D - Denver Three pence 1942 and 1943 only, Sixpence 1942 and 1943 only.
PL - Royal Mint
, London, both Three pence and Sixpence for 1951 only.
Dot - Before the S of shilling denotes Perth mint for the year 1946 only.
Star - A "*" above the date of the 1921 shilling denotes Sydney mint.